package com.lagou.sqlSession;

import com.lagou.pojo.Configuration;
import com.lagou.pojo.MappedStatement;

import java.beans.IntrospectionException;
import java.lang.reflect.*;
import java.sql.SQLException;
import java.util.List;

/**
 * @description:
 * @author: panrongxiang
 * @date: 2021/7/1
 */
public class DefaultSqlSession implements SqlSession {
    private Configuration configuration;

    public DefaultSqlSession(Configuration configuration) {
        this.configuration = configuration;
    }

    @Override
    public <E> List<E> selectList(String statementid, Object... params) throws SQLException, IllegalAccessException, IntrospectionException, InstantiationException, NoSuchFieldException, InvocationTargetException, ClassNotFoundException {

        //将要去完成对simpleExecutor里的query方法的调用
        SimpleExecutor simpleExecutor = new SimpleExecutor();
        MappedStatement mappedStatement = configuration.getMappedStatementMap().get(statementid);
        List<Object> list = simpleExecutor.query(configuration, mappedStatement, params);

        return (List<E>) list;
    }

    @Override
    public <T> T selectOne(String statementid, Object... params) throws SQLException, IllegalAccessException, IntrospectionException, InstantiationException, ClassNotFoundException, InvocationTargetException, NoSuchFieldException {
        List<Object> objects = selectList(statementid, params);
        if (objects.size() == 1) {
            return (T) objects.get(0);
        } else {
            throw new RuntimeException();
        }


    }

    @Override
    public  int insert(String statementid, Object... params) throws ClassNotFoundException, SQLException, IllegalAccessException, NoSuchFieldException {
        return executeUpdate(statementid, params);
    }

    @Override
    public int deleteById(String statementid, Object... params) throws ClassNotFoundException, SQLException, IllegalAccessException, NoSuchFieldException {
        return executeUpdate(statementid, params);
    }

    @Override
    public int updateById(String statementid, Object... params) throws ClassNotFoundException, SQLException, IllegalAccessException, NoSuchFieldException {
        return executeUpdate(statementid, params);
    }

    private int executeUpdate(String statementid, Object[] params) throws SQLException, NoSuchFieldException, ClassNotFoundException, IllegalAccessException {
        SimpleExecutor simpleExecutor = new SimpleExecutor();
        MappedStatement mappedStatement = configuration.getMappedStatementMap().get(statementid);
        return simpleExecutor.update(configuration, mappedStatement, params);
    }


    @Override
    public <T> T getMapper(Class<?> mapperClass) {
        //使用JDK动态代码来为Dao接口生成代理对象,并返回
        Object proxyInstance = Proxy.newProxyInstance(DefaultSqlSession.class.getClassLoader(), new Class[]{mapperClass}, new InvocationHandler() {
            @Override
            public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
                //底层都还是去执行JDBC代码   根据不同情况,来调用selectList 或者 selectOne
                //1.准备参数 statementid sql语句的唯一标识  namespace.id=接口全限定名.方法名
                //方法名
                String methodName = method.getName();
                String className = method.getDeclaringClass().getName();

                String statementid = className + "." + methodName;

                //2.准备参数
                //获取被调用方法的返回值类型
                Type genericReturnType = method.getGenericReturnType();
                //判断是否进行了  泛型类型参数化
                if (method.getName().contains("find")) {
                    if (genericReturnType instanceof ParameterizedType) {
                        List<Object> objects = selectList(statementid, args);
                        return objects;
                    }

                    return selectOne(statementid, args);
                } else {
                    return executeUpdate(statementid, args);
                }
            }
        });
        return (T) proxyInstance;
    }
}
